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People with HIV age 50 and older see markers of bone and kidney health improve when they switch from a regimen containing the older version of the drug tenofovir to an antiretroviral (ARV) combination including the new version, aidsmap reports.

The generic drug tenofovir is one of the most commonly used ARVs, a component of many of the major single-tablet combination regimens, as well as Truvada (tenofovir disoproxil fumarate, or TDF/emtricitabine). The older version of the ARV, known as TDF, is associated with lowered kidney function and reduced bone mineral density.

An updated version of TDF, tenofovir alafenamide, or TAF, was first approved in November 2015 as a component of Genvoya (elvitegravir/cobicistat/emtricitabine/ TAF). Gilead Sciences has since secured approval for updated versions of all its combination tablets containing TDF, with the exception of Atripla (efavirenz/TDF/emtricitabine), which is no longer a preferred first-line therapy for HIV. In November 2016, a standalone version of TAF was approved under the brand name Vemlidy for the treatment of hepatitis B virus (HBV).

Researchers conducted a study of 663 people taking Truvada plus a third ARV, although not as a single-tablet regimen. Upon starting the study they had a fully suppressed viral load and kidney function near normal, with an estimated glomerular function (eGFR) of at least 50 milliliters per minute.

Findings of a substudy of 294 participants age 50 or older were presented at the IDWeek 2016 conference in New Orleans. The median age of the cohort was 55 and ranged between 50 and 79.

The participants were randomized to stay on Truvada or to switch to Descovy (emtricitabine/TAF) and stay on their third ARV. Nearly half of the participants used a Norvir (ritonavir)-boosted third agent in their HIV regimen while the others took unboosted third agents. Those on the boosted third agent took 10 milligrams of TAF while those who took an unboosted third agent took 25 mg of TAF.

After 48 weeks of treatment, 96 percent of those who took Descovy and 94 percent of those who took Truvada had a fully suppressed viral load.

Both regimens were safe and generally well tolerated. Indicators of bone and kidney health suggested TAF was less toxic than TDF, however.

Those who switched to Descovy experienced an 8.8 ml/min increase in median eGFR compared with a median 2.5 ml/min increase in those who stayed on Truvada. Various urine biomarkers suggested that kidney health improved for those taking Descovy and worsened for those taking Truvada.

Spine and hip bone mineral density increased by an average 1.9 percent and 1 percent among those who switched to Descovy, respectively, and dropped an average of 0.2 percent and 0.3 percent among those who stayed on Truvada.